What is Selenium? A student at school level will answer this as “Selenium is a chemical element with an atomic number 34 in the periodic table”, but the same student finds a different answer for it when he lands in the technical environment. So, what is that different answer? The answer is simple, Selenium is an automation testing tool for web applications. 

What is Selenium?

Have you ever thought of why testing plays a critical role in software development lifecycle? Have you ever heard of automation testing? If yes, then you might be aware of what Selenium is. Selenium is considered as a counterpart of Automation testing. If no, then it is time for you to go ahead and get a read on this entire article to understand the importance of Selenium in IT world. This can change your career drastically and put you on the map of the IT industry.

Software testing is a very critical factory for a successful software product run. It must be tested thoroughly before delivering it to users for software product’s effective performance. All the software in markets are properly tested, yet they have defects. It is very important to deliver the software without any defects and all test engineers try to catch them before software release to avoid any issues in future. Automation testing has become very famous due to its various advantages. It increases the effectiveness and efficiency of the software.

Selenium is one of the widely used automation testing tools because of its various advantages. Testers prefer Selenium over any other tool due to its ease of use, availability and simplicity. Testers lives have been made easier with the introduction of Selenium for automated testing. It has attracted many eyeballs and become a favourite tool among automation testers.

Before travelling into this blog of Selenium automation testing, you must be introduced to some basics such as 


What is Software Testing?

In simple terms, one can define testing as checking or measuring the quality, reliability, or performance of a product before making it available for normal use. For example, most of the products ranging from a small pin to spacecraft are tested before they are made available. 

Today, we are in the world of technology dominated by software powered machines and applications. We expect them to work as we want every time and everywhere. Are we sure will they work? The answer lies in Software Testing.

Software Testing can be defined as investigating or checking the quality of software applications before their release to the user. The same testing is applicable even for web applications as most of the businesses today are internet or web-based. So why should we do testing for web applications? 
Imagine a scenario where you place an order on online shopping, but you are not able to track the status of your order. This may be due to a bug or error in the web application’s backend code. So there is a need for testing the code to avoid such bugs or errors. Selenium tool offers such testing for web applications.

Types of Software Testing

  1. Manual Testing
  2. Automation Testing

1. Manual Testing

Traditionally software testing is carried out by Quality Assurance (QA) personnel by writing specific lines of code usually called, test cases. These test cases must be executed manually for every transaction using different types of attributes and datasets. The result of the test cases, either success or failure must be recorded manually. The major drawback of manual testing is the high chance of human errors while the repetition of test case execution which results in low product quality. 

2. Automation Testing

The drawback of manual testing resulted in automation testing where a tool is used to execute test cases avoiding manual interference for every transaction. Further, we can configure the test cases so that they can be tested irrespective of operating systems, platforms and web browsers. The result of a test case can also be automated by scheduling it to a particular time of the day.

Manual Testing vs. Automation Testing

  Manual Testing Automation Testing
  • No testing experience is needed. 
  • Quality can be improved easily
  • Customer’s flow is focused mainly
  • Faster than manual testing
  • Identifies more test cases and defects in less time
  • All workflows are focussed
  • Product quality is high
  • High accuracy in results
  • Product quality is low
  • A Higher count of defects
  • All test cases and defects may not be identified
  • No accuracy in results
  • Time-consuming
  • Test cases must be written by testing      scripter
  • Testing platform is needed
  • Manual tests must be written first and then automated

Here is the end to basics of testing, types of testing and their differentiation.  Now, the main focus of this blog is to introduce you the basics of Selenium, its components, comparison of Selenium with other top testing tools and concluding why selenium is best among them.

What is Selenium?

As said at the beginning of this blog, Selenium is an automation testing tool for web applications. It is a free source automation testing tool that is used to automate the tests on web browsers.

You may be wondering why only web applications and why not mobile and desktop software applications. There are other tools like Rational Functional Tester (RFT), Unified Functional Testing (UFT) (former QTP), Watir, Tricentis and so on for testing mobile and desktop software applications.

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The first Selenium testing tool was developed by Jason Huggins in the year 2004 who was an engineer that time at ThoughtWorks. As a part of his work on testing web applications, Jason has realized that manual testing has become more inefficient due to repetitions of same test cases. 

This led to the creation of a JavaScript program called “JavaScriptTestRunner” to control browser actions automatically. Observing the potential in his idea, Jason made this JavaScript program as open-source and renamed it as Selenium Core.

[Related Page: Blue Prism VS Selenium]

Selenium Components

Why the name Selenium?

The name Selenium has been adapted from a funny mail sent by Jason to his team. During the development of Selenium, there was a popular testing tool by a company named Mercury Interactive (it was the same company who developed QTP and later it was sold to HP). Since Selenium cures Mercury poisoning, Jason has suggested the same name. The team has adopted it and it is how Selenium got its present name.

[Related Page: Salesforce Automation Testing With Selenium]

Selenium Suite

It is proper to call Selenium as Selenium Suite since it is a collection of four different tools or components namely.

  • Selenium Integrated Development Environment (IDE)
  • Selenium Remote Control (RC)
  • Selenium WebDriver
  • Selenium Grid

1. Selenium Integrated Development Environment (IDE)

Selenium Integrated Development Environment (IDE) is the only simplest and easy to learn component or tool in the Selenium automation testing suite. IDE is a Firefox plug-in which can be installed easily to record and execute frequent test cases quickly. The user interactions with the web browser are recorded and test cases are created based on these recordings. You can playback these test cases repeatedly. Though Selenium IDE is simple, it cannot be used as a prototype for writing advanced test cases. 

Selenium IDE was initially created by Shinya Kasatani of Japan as a Firefox plug-in that records and playbacks the user-browser interactions. So initially Selenium IDE was also known as Selenium Recorder.  The other idea behind the development of Selenium IDE was to speed up the creation of test cases. Later in 2006, he donated this Selenium IDE to the Selenium Project.

[Related Page: Installation of Selenium IDE]

2. Selenium Remote Control (RC)

Selenium Remote Control has been developed to overcome the issue of Same Origin Policy (SOP). Under this policy, a JavaScript code cannot access the elements of other domain that are different from its parent domain. For example, if a JavaScript program uses a code written for our site www.mindmajix.com, then SOP allows it to access the pages site such as mindmajix.com/all-courses or mindmajix.com/blog, prohibiting the access to other domains like google.com.

[Related Page: Learn Java Basics for Selenium]

Before Selenium RC came into existence, testers used to locally install the copies of Selenium Core and web server with web applications to be tested so that, they both would belong to the single domain.  Observing this, Paul Hammant, another engineer at ThoughtWorks, created Selenium RC which turned out to be the permanent solution for the problem of the SOP. 

How does Selenium RC solve the SOP issue?

Selenium RC tricked the browser to believe that both Selenium Core and web server with the web application to be tested belong to the same parent domain. This has been achieved by involving a proxy HTTP server making RC as a dual-component tool – Selenium RC Server and Selenium RC Client.

Selenium RC was the first flagship testing tool of Selenium project which allows user preferred languages to write the test cases. Selenium RC 2.25.0 supports the following list of languages – 

  • C
  • Java
  • Perl
  • PHP
  • Python and 
  • Ruby

So, it is also called as Selenium 1. But, the major drawback of RC is, it consumes more time for every server communication taking hours of time to complete even a single test. 

Unfortunately, due to the depreciation, Selenium RC has been renamed as Selenium HQ and shifted to a legacy package. It means, we can still work with Selenium RC, but no support can be availed for it. You may be wondering what would be the replacement for RC. 

3. Selenium WebDriver

Selenium WebDriver was created by Simon Stewart in 2006 as the replacement for Selenium RC. Unlike IDE and RC, Selenium WebDriver provides an interface for creating and executing test cases. These test cases are created in such a way that, web page elements can be easily identified and necessary actions are performed. 

In 2008, Selenium WebDriver has been merged with Selenium RC and evolved as a more potent tool called as Selenium 2, keeping WebDriver as the core. So, Selenium WebDriver can be called as an upgrade version to RC as it employs a contemporary and consistent browser automation approach. WebDriver is much faster than RC because it directly calls the browser whereas RC needs a server to interact with the browser and depends on JavaScript for automated web application testing. Each web browser has its own WebDriver such as,

  • Chrome Driver
  • Gecko Driver (Firefox)
  • HTM Unit Driver
  • IE Driver
  • Opera Driver and 
  • Safari Driver

Selenium WebDriver supports the languages similar to that of Selenium RC

  • C#
  • Java
  • Perl
  • PHP
  • Python and 
  • Ruby

4. Selenium Grid

Selenium Grid is one of the Selenium testing tools used in combination with Selenium RC to execute test cases remotely. It was created by Patrick Lightbody to deal with the minimization of execution times of test cases. Selenium Grid was initially named as Hosted QA and was a part of Selenium 1. 

Selenium Grid uses Hub-Node design to support parallel execution of multiple test cases on multiple machines which are remotely located. In Hub-Node design, one machine is treated as Hub which controls the test cases running on different browsers inside different operating systems. The other machines are treated as Nodes on which test cases can be written in user preferred programming languages.

Here comes the end of the basic introduction of Selenium QA tool and its components. Now you will be introduced to other testing tools apart from the Selenium tool and why Selenium is the best among them by comparing the top five testing tools.

Selenium Tutorial

Why Selenium is the best automation testing tool?

Why Selenium is the best automation testing tool? Before getting the answer to this question, you must be introduced to the top ten automation testing tools. The following is the list of top testing tools apart from Selenium testing tool. It includes both commercial and free source automation testing tools.

  • Katalon Studios
  • Unified Functional Testing (UFT) (former QTP)
  • Test Complete
  • Rational Functional Tester
  • Watir
  • Test Plant 
  • Tricentis
  • Ranorex
  • Robot Framework

Comparison of Top Five Automation Testing Tools

Let us Compare the Top Five Automation Testing Tools
Unified Functional Testing
Katalon Studio
Applications to test
Web Applications
Web, Desktop, Mobile and Packaged applications
Web applications
Web, Mobile and Desktop applications
Web and Mobile applications
Operating Systems
Windows, Linux,
Windows, Linux,
Windows, Linux,
C#, Java, Perl, PHP, Python, and Ruby
C++, C#, Delphi, JavaScript, Jscript, Python,  and VBScript
Groovy/ java
Ease of Installation
Advanced skills are required to install
Complex to install
Require advanced skills to integrate different tools
Easy to install
Easy to install
Ease of use
Advanced skills to use
Training is needed
Advanced skills to use
Training is needed
Easy to use
Programming skills
Advanced skills to integrate different tools
Required skills for advanced test cases
Advanced skills to integrate different tools
Required skills for advanced test cases
Required skills for advanced test cases

From the above comparison, it is clear that Selenium QA tool has more advantages than other testing tools. The following shows you the pros and cons of each Selenium component and the overall advantages of Selenium automation testing tool which makes it the best among other tools.

Pros and Cons of Selenium Components

Pros and cons of Selenium IDE are as follows 

Selenium IDE

Pros Cons
It is simple, easy install and use. Only available for Firefox.
No prior programming knowledge is needed, though basic knowledge of DOM and HTML is required. Designed to create test prototypes.
Test cases can be exported to usable formats in Selenium WebDriver and RC. Conditional operations and iterations are not supported.
Extensions are supported. Execution of test cases is slow compared to WebDriver and RC.
Built-in test results reporting and help modules Does not test dynamic web applications.
Supports appropriate scripting, reporting and debugging besides recording and replaying. Data-driven testing is not supported.
Can export recorded tests in different programming languages like Java, Python, Ruby etc. Programming logic is not used in scripting test cases.

Pros and cons of Selenium RC are as follows :

Selenium RC

Supports cross-browser testing.
Complicated installation than IDE.
Conditional operations and iterations are supported.
Prior programming knowledge is needed.
Supports data-driven testing
Selenium RC must be needed to run test cases.
Complete and matured API
API contains confusing and redundant commands.
New browsers are readily supported.
Browser interaction is less realistic.
Execution speed is more than IDE.
Slower execution speed than WebDriver
Supports user preferred languages.
Uses JavaScript and results are inconsistent.

Pros and cons of Selenium WebDriver are as follows:

Selenium WebDriver

Pros Cons
Easy installation compared to Selenium RC. Complicated installation than Selenium IDE.
Direct browser communication. Prior programming knowledge is required.
More realistic browser interaction. No immediate support for new browsers.
No separate component such as RC server is needed. No mechanism to track runtime messages.
Execution time is faster than RC and IDE. Image testing is not possible.
Supports testing on different platforms like Mac, Linux, Windows, iOS, and Android. No detailed test results and reports.

However, the drawbacks such as image testing and generation of detailed test reports can be surmounted by integrating with other frameworks.  We can use Sikuli for image testing and TestNG to generate detailed test reports.

Selenium Grid has the following pros and cons,

Selenium Grid

Pros Cons
Supports simultaneous execution of test cases in multiple environments and browsers. The code is executed only on the local machines where test cases are launched.
Captures the screenshots of browsers at different stages of test case execution. The remote machines only receive the browser control commands.
Provides tools needed to diagnose the failures and rebuild a similar environment for new test execution. Large quantities of node servers result in performance depreciation.
Selenium Grid saves time extremely as it uses Hub-Node design. Considerable efforts and time are required for initial operation of parallel testing.


Selenium Interview Questions

Advantages of Selenium

Selenium Advantages

  • The following list showcases the advantages of Selenium testing tool that makes it best among other automation testing tools.
  • Selenium is an open-source automation testing tool and it is free of cost to use.
  • Selenium provides high tester flexibility to write advanced and complex test cases.
  • Supports test scripts written in any user-preferred languages such as C#, Java, Perl, PHP, Python, and Ruby
  • Supports test case execution on multiple operating systems such as Windows, Linux, Android, Mac, and iOS.
  • Supports testing on different web browsers such as Chrome, Firefox, Internet Explorer (IE), Opera, and Safari.
  • Test cases can be executed while the browser window is minimized.
  • Selenium supports parallel test execution.
  • Selenium can be integrated with TestNG and JUnit to generate test reports and manage test cases.
  • Selenium can be integrated with Jenkins, Docker, and Maven to attain continuous testing. 

Apart from the above advantages, Selenium testing tool has some shortcomings such as,

  • Selenium can test only web applications. It cannot test software applications and other desktop applications. 
  • Selenium cannot access the web elements outside the web applications that are under test.
  • No guaranteed user support is available. We have to depend on customer communities.
  • Selenium independently does not support image testing. It must be integrated with Sikuli for image testing.


Selenium testing tool has both advantages and shortcomings in comparison to other automation testing tools. But, Selenium overshadows other testing tools in areas of –

  • Cost – Selenium comes at free of cost as it is an open-source testing tool.
  • Parallel Testing – Tester can execute test scripts on multiple machines simultaneously.
  • Flexibility – Selenium supports test scripts in multiple languages, execution on multiple browsers and operating systems.

On the conclusion note, the above three major features of Selenium and its different components made Selenium as one of the best automation testing tool.

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